pytest plugin for testing mypy types, stubs, and plugins
Installation
This package is available on PyPI
pip install pytest-mypy-plugins
and conda-forge
conda install -c conda-forge pytest-mypy-plugins
Usage
Running
Plugin, after installation, is automatically picked up by pytest therefore it is sufficient to just execute:
pytest
Paths
The PYTHONPATH and MYPYPATH environment variables, if set, are passed to mypy on invocation. This may be helpful if you are testing a local plugin and need to provide an import path to it.
Be aware that when mypy is run in a subprocess (the default) the test cases are run in temporary working directories where relative paths such as PYTHONPATH=./my_plugin do not reference the directory which you are running pytest from. If you encounter this, consider invoking pytest with --mypy-same-process or make your paths absolute, e.g. PYTHONPATH=$(pwd)/my_plugin pytest.
You can also specify PYTHONPATH, MYPYPATH, or any other environment variable in env: section of yml spec:
- case: mypy_path_from_env
main: |
from pair import Pair
instance: Pair
reveal_type(instance) # N: Revealed type is 'pair.Pair'
env:
- MYPYPATH=./pytest_mypy_plugins/tests/fixtures
What is a test case?
In general each test case is just an element in an array written in a properly formatted YAML file. On top of that, each case must comply to following types:
| Property | Type | Description |
|---|---|---|
case |
str |
Name of the test case, complies to [a-zA-Z0-9] pattern |
main |
str |
Portion of the code as if written in .py file |
files |
Optional[List[File]]=[]* |
List of extra files to simulate imports if needed |
disable_cache |
Optional[bool]=False |
Set to true disables mypy caching |
mypy_config |
Optional[Dict[str, Union[str, int, bool, float]]]={} |
Inline mypy configuration, passed directly to mypy as --config-file option |
env |
Optional[Dict[str, str]]={} |
Environmental variables to be provided inside of test run |
parametrized |
Optional[List[Parameter]]=[]* |
List of parameters, similar to @pytest.mark.parametrize |
skip |
str |
Expression evaluated with following globals set: sys, os, pytest and platform |
expect_fail |
bool |
Mark test case as an expected failure, like @pytest.mark.xfail |
regex |
str |
Allow regular expressions in comments to be matched against actual output. Defaults to "no", i.e. matches full text. |
(*) Appendix to pseudo types used above:
class File:
path: str
content: Optional[str] = None
Parameter = Mapping[str, Any]
Implementation notes:
mainmust be non-empty string that evaluates to valid Python code,contentof each of extra files must evaluate to valid Python code,parametrizedentries must all be the objects of the same type. It simply means that each entry must have exact same set of keys,skip- an expression set inskipis passed directly intoeval. It is advised to take a peek and learn about howevalworks.
Example
1. Inline type expectations
# typesafety/test_request.yml
- case: request_object_has_user_of_type_auth_user_model
main: |
from django.http.request import HttpRequest
reveal_type(HttpRequest().user) # N: Revealed type is 'myapp.models.MyUser'
# check that other fields work ok
reveal_type(HttpRequest().method) # N: Revealed type is 'Union[builtins.str, None]'
files:
- path: myapp/__init__.py
- path: myapp/models.py
content: |
from django.db import models
class MyUser(models.Model):
pass
2. @parametrized
- case: with_params
parametrized:
- val: 1
rt: builtins.int
- val: 1.0
rt: builtins.float
main: |
reveal_type({[ val }}) # N: Revealed type is '{{ rt }}'
3. Longer type expectations
- case: with_out
main: |
reveal_type('abc')
out: |
main:1: note: Revealed type is 'builtins.str'
4. Regular expressions in expectations
- case: expected_message_regex_with_out
regex: yes
main: |
a = 'abc'
reveal_type(a)
out: |
main:2: note: .*str.*
5. Regular expressions specific lines of output.
- case: expected_single_message_regex
main: |
a = 'hello'
reveal_type(a) # NR: .*str.*
Options
mypy-tests:
--mypy-testing-base=MYPY_TESTING_BASE
Base directory for tests to use
--mypy-ini-file=MYPY_INI_FILE
Which .ini file to use as a default config for tests
--mypy-same-process Run in the same process. Useful for debugging, will create problems with import cache
--mypy-extension-hook=MYPY_EXTENSION_HOOK
Fully qualified path to the extension hook function, in case you need custom yaml keys. Has to be top-level.
--mypy-only-local-stub
mypy will ignore errors from site-packages
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